3rd Place: Ruby’s Night Light
I am a mechanical engineer and this was my first forray
into an electronics project. I am the father of three young
girls and don't find a lot of time for building, but I have been
looking for a project that they might enjoy with the end
project being to encourage them to get into building. I have
been inspired by numerous articles in Nuts & Volts and
Make Magazine to construct something with an Arduino.
I was particularly inspired by Gene Scogin's article in Make
Vol. 13 for an analog clock.
While I was working on a modified version, my
youngest daughter started having trouble waking up early in
the mornings, and since she couldn't read a clock
(too young to tell time plus poor vision) she
would call for her parents to find out if it was
time to get up. After waking up enough to
summon us, she would often have a hard time
getting back to sleep. After responding to a
number of these 2:00 am calls, I decided it was
time for an engineering intervention. I had the
idea that a color changing nightlight could help
her know immediately what time it was — even
through blurry eyes — so that she could
confidently go back to sleep knowing she wasn't
missing the fun of a new day.
I started with Scogin's code and added some
code that converted HSV color values to RGB
values. Since the Arduino’s PWM output
channels can provide enough current to power five LEDs,
I used a simple transistor circuit to drive them.
(I sill used the Arduino’s onboard voltage regulator for
power.) The transistors and LED current-limiting resistors
were mounted on a perfboard with a header to connect to
the Arduino (specifically, a Bare Bone Board variant).
I had been looking for an excuse to use Ponoko to
make something, and this was my opportunity. I wanted to
keep the design simple — but personal to my daughter — so
I used Inkscape to lay out her name, and had Ponoko laser
cut it in clear acrylic. I drilled holes around the perimeter to
mount the LEDs, and frosted the plastic by sanding it. I used
square acrylic tubing to make a border to cover the LEDs
and wiring, and built the base to hold the microcontroller
(out of acrylic also). I had hoped the discrete LEDs would blend better, but the border wasn't big enough, so you can still
easily discern the individual colors around the edge.
I have started working on a modified version for my second daughter, and it will utilize tri-color LEDs in a single
package with more border for better blending. I might try just etching the name instead of cutting it through.
November 2011 45